[postgis-devel] New polygon constructors

[david techer]

Sandro

is Regression test available on CVS for this function?

--david;
-------------------------------------------------
Jean David TECHER
e-mail: davidtecher(at)yahoo(dot)fr
site: http://techer.pascal.free.fr/postgis/
-------------------------------------------------



strk at refractions.net a écrit :

>Ok, I wrapped polygonize_garray using algorithm suggested
>by Carl Anderson to ensure valid output. We now have
>tree more functions:
>
>	- BuildArea(geometry)
>
>	  Takes any geometry, extract linework and returns
>	  either a Polygon or MultiPolygon depending on input.
>
>	- BdPolyFromText(text, integer)
>	- BdMPolyFromText(text, integer)
>
>	  OGC standard functions, require MULTILINESTRING WKT
>	  in input (will raise an exception otherwise).
>	  The single-geom version will raise an exception
>	  if a MultiPolygon is returned (they both calll
>	  BuildArea internally)
>
>So, what you'll be using is BuildArea(), but the OGC versions
>are there to be standard compliant.
>
>Regress test has been added for the tree functions.
>
>--strk;
>
>	
>
>On Fri, Dec 09, 2005 at 10:46:19AM -0700, Charlie Savage wrote:
>  
>
>>I'd vote for wrapping polygonize_garray so that their is only one 
>>implementation of the code.
>>
>>Charlie
>>
>>strk at refractions.net wrote:
>>    
>>
>>>On Fri, Dec 09, 2005 at 04:23:59PM +0100, strk at refractions.net wrote:
>>>...
>>> 
>>>      
>>>
>>>>Nonetheless, many items in the TODO list are completely missed:
>>>>   
>>>>        
>>>>
>>>...
>>> 
>>>      
>>>
>>>>- OGC polygon constructors
>>>>   
>>>>        
>>>>
>>>I'm approaching this. SFSQL 1.1 contains the following information
>>>about these:
>>>
>>> 
>>>      
>>>
>>>>As an optional feature, an implementation may also support `building' of
>>>>Polygon or MultiPolygon values given an arbitrary collection of possibly
>>>>intersecting rings or closed LineString values.  Implementations that
>>>>support this feature should include the following functions:
>>>>
>>>>BdPolyFromText(multiLineStringTaggedText String, SRID Integer): Polygon
>>>>
>>>>  Construct a Polygon given an arbitrary
>>>>  collection of closed linestrings as a
>>>>  MultiLineString text representation.
>>>>
>>>>BdMPolyFromText(multiLineStringTaggedText String, SRID Integer): 
>>>>MultiPolygon
>>>>
>>>>  Construct a MultiPolygon given an
>>>>  arbitrary collection of closed linestrings as a
>>>>  MultiLineString text representation.
>>>>   
>>>>        
>>>>
>>>Given these specs I think we can avoid use of GEOS for the construction,
>>>as the only required thing is to find out what is an hole and
>>>what is a shell. C code for this is already present in the loader.
>>>
>>>The alternative would be using just a comple of wrappers
>>>to the polygonize_garray() function.
>>>
>>>Thoughts ?
>>>
>>>--strk;
>>>
>>>/"\    ASCII Ribbon Campaign
>>>\ /    Respect for low technology.
>>> X     Keep e-mail messages readable by any computer system.
>>>/ \    Keep it ASCII. 
>>>
>>>_______________________________________________
>>>postgis-devel mailing list
>>>postgis-devel at postgis.refractions.net
>>>http://postgis.refractions.net/mailman/listinfo/postgis-devel
>>>
>>>
>>> 
>>>      
>>>
>
>
>
>  
>
>>_______________________________________________
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>>    
>>
>
>
>  
>

	

	
		
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